Initial commit: notification-elements-demo app

Interactive Angular 19 demo for @sda/notification-elements-ui with
6 sections: Bell & Feed, Notification Center, Inbox, Comments &
Threads, Mention Input, and Full-Featured layout. Includes mock
data, dark mode toggle, and real-time event log.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

node_modules/thingies/lib/Locks.d.ts

@@ -0,0 +1,25 @@
+/**
+ * Creates a lock manager, which can create exclusive locks across browser tabs.
+ * Uses `window.localStorage` by default to lock across tabs.
+ *
+ * Below example, will wait for 5 seconds to acquire a lock, and then execute
+ * the function once lock is acquired and release the lock after function
+ * execution. It will fail with `LOCK_TIMEOUT` error if lock is not acquired
+ * within the 5 seconds. The lock will acquired for 2 seconds (default 1000ms).
+ *
+ * ```ts
+ * Locks.get().lock('my-lock', 2000, 5000)(async () => {
+ *   console.log('Lock acquired');
+ * });
+ * ```
+ */
+export declare class Locks {
+    protected readonly store: Record<string, string>;
+    protected readonly now: () => number;
+    protected readonly pfx: string;
+    static get: () => Locks;
+    constructor(store?: Record<string, string>, now?: () => number, pfx?: string);
+    acquire(id: string, ms?: number): (() => void) | undefined;
+    isLocked(id: string): boolean;
+    lock(id: string, ms?: number, timeoutMs?: number, checkMs?: number): <T>(fn: () => Promise<T>) => Promise<T>;
+}